Wassily Leontief met with decades of success for the development of input-output analysis, and yet he remained a staunch critic of the economics profession throughout his life. To understand his success, its limits, and the origins of his discontent, this article separates the scientific activities of input-output from the system of belief built around it, and from the institutions set up to advance Leontief's research program. This leads to considering the interaction of input-output with other research programs through three poles: the scientific debate, the collision of belief systems about the world, and an institutional fight for funds and researchers. The end result is a picture of how Leontief managed to build a successful research program in which scientific inquiry led to beliefs about the world that were able to justify building institutions promoting input-output, in an environment of competition and cooperation.